Abstract

Synovial fluid is a potential source of novel biomarkers for many arthritic disordersinvolving joint inflammation, including juvenile idiopathic arthritis. We first compared thedistinctive protein ‘fingerprints’ of local inflammation in synovial fluid with systemicprofiles within matched plasma samples. The synovial fluid proteome at the time of jointinflammation was then evaluated across clinical subgroups to identify early diseaseassociated proteins. We measured the synovial fluid and plasma proteomes using the two dimensional fluorescence difference gel electrophoresis approach. Image analysis software was used to highlight the expression levels of joint and subgroup associated proteins acrossthe study cohort (n=32). A defined subset of 30 proteins had statistically significantdifferences (p<0.05) between sample types such that synovial fluid could be differentiatedfrom plasma. Furthermore distinctive synovial proteome expression patterns segregatepatient subgroups. Protein expression patterns localized in the chronically inflamed jointtherefore have the potential to identify patients more likely to suffer disease which willspread from a single joint to multiple joints. The proteins identified could act as criteria toprevent disease extension by more aggressive therapeutic intervention directed at an earlierstage than is currently possible.